The present invention relates to a holographic optical element for measuring the dimension and position of an object with the aid of a deflected light beam that sweeps across a specific angular range, the element having an interference pattern in one section which can be created in a manner known per se through simultaneous exposure to a fan-shaped reference wave front, generated by a monochromatic and coherent laser light source, and a parallel wave front that is also generated by the same monochromatic, coherent laser light source, but hits the element at a different angle than the reference wave front, as well as through the subsequent development.
For the purpose of this document, a holographic optical element of this type is henceforth referred to as an HOE.
A special holographic laboratory is generally required in order to produce an HOE. The equipment by and large corresponds to that of a photo laboratory, with the exception that only monochromatic, coherent laser light is used. Film plates (coated glass plates) are used to produce holograms and, in particular an HOE. These plates are exposed to selected wave fronts and are subsequently developed, depending on the film base that is used.
An HOE of this type is described, among other things, in European Patent Application No. EP-A 0 245 198. This reference also contains detailed instructions for producing an HOE used in a device and with a method for generating light beams for measuring the dimension and/or position of an object in the deflection displacement region of this light beam.
If the HOE, produced as described in the above, is exposed to a suitable laser reference wave front, then the other wave front used during the picture taking is correspondingly reconstructed.
With the above-mentioned device, the object to be measured, in particular a cable or the like, can be measured only in one direction.